Many electrical and electronic devices are composed of a fixed body and a moving part. The moving part may be, for example, a rotational part such as washing machine door or a refrigerator door etc., or may be a translational moving part, such as a refrigerator drawer. End users of such equipment increasingly require ease of use and improved aesthetics, consequently, many of the control and display functions are integrated on the moving parts.
Physical wire connections between the fixed body and the moving part, used to transfer electrical energy, are subject to wear and decreased life due to the repeated motion of the moving part. For these reasons, non-contact power transmission is used.
As is known in the art, non-contact transmission may be achieved by electromagnetic coupling between a transmitting coil and a receiving coil. An electric field or magnetic field is created between the transmitting coil and the receiving coil to transmit the electrical energy. In these applications, the strength and consistency of the field is critically important.
It is conventional to use a single transmitter coil and a single receiver coil. The coils, however, are limited by the size of the installation location and environment. Furthermore, the coupling efficiency of one to one coils will change as the position of the coil changes, which necessarily restricts the efficiency and power transmission of the system.